Respiratory System

The respiratory system of the human body is responsible for the distribution of the air inhaled and exhaled throughout a person's life. The respiratory system includes the nose, throat, voice box, wind pipe, and lungs.

Each time a person inhales, or breathes in air, several kinds of gases enter the body. The most important is oxygen because it keeps a person alive, and the cells of the body need it for energy and growth. The air enters through the nose and mouth and the lungs fill up and then empty out. When the air is inhaled there are tiny hairs in the nose called cilia that filter the air. The air is also warmed and moistened as it travels through the nose. Cilia also protects other parts of the respiratory passages, filtering out dust and other particles.

The inhaled air travels through the windpipe, which is called the trachea. The human body contains two lungs. The lungs are pink, mushy, and like a sponge. The lungs are protected by the rib cage and keeps them protected and safe. The lung on the left side of the body is smaller than the right lung, which allows room for a person's heart. Beneath the lungs is a muscle called the diaphragm. It works with the lungs to allow a person to inhale and exhale. When a person breathes in the diaphragm shrinks and levels out as the lungs fill up with air.

The end of the trachea is located between the two lungs. At the bottom of the trachea are a couple of large tubes called bronchi. The bronchi lead into the lungs. One tube sends air into the left lung, and the other tube sends air into the right lung.

Once the air travels through the bronchi, it will branch off into smaller tubes called bronchioles. The bronchioles are about the thickness of a hair, and there are about 30,000 in each lung. From the bronchioles the air then continues its journey to tiny air sacs located throughout the lungs. The tiny air sacs are called alveoli.

The 600 million alveoli are covered with very tiny blood vessels called capillaries. It is in this area of the lungs between the alveoli and capillaries the exchange of air takes place. Alveoli allow the air to pass into the blood cells of the body, first traveling through the heart carried by red blood cells. The oxygen enters the blood through the tiny capillaries. The heart then takes the blood filled with oxygen and sends it out to all the cells of the body.

When a person exhales or breathes out everything will happen in reverse. The diaphragm relaxes and the lungs become smaller. The cells in the body have received the oxygen it needs, but carbon dioxide must leave the body. This time, wastes enter the alveoli through the capillaries, back through the bronchioles and bronchi, and then the trachea and out through the nose and mouth. The air is warm because it heats up as it travels through the body.

Finally, the lungs are also important for talking. The larynx is located above the trachea, which is often called the voice box. Vocal cords across the larynx open and close, and then vibrate, to create the sounds as air flows between them. The amount of air exhaled determines the loudness of a sound.

In summary, there are many parts of the respiratory system working together to distribute oxygen throughout the body, as well as the lungs being necessary for a person's ability to talk. It is important to keep the lungs healthy and strong.

A: Alveoli
B: Cilia
C: Bronchioles
D: Bronchi

A: Trachea
B: Diaphragm
C: Bronchi
D: Cilia

A: Bronchi and bronchioles
B: Cilia and trachea
C: Alveoli and capillaries
D: Larynx and windpipe

A: Trachea
B: Throat
C: Diaphragm
D: Larynx

A: Bronchi
B: Bronchioles
C: Alveoli
D: Capillaries

A: Trachea, bronchioles, bronchi, alveoli, capillaries
B: Trachea, bronchi, bronchioles, alveoli, capillaries
C: Trachea, alveoli, capillaries, bronchi, bronchioles
D: Trachea, larynx, bronchi, bronchioles, alveoli

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